Half-moon marks (commonly known as little suns) are actually a natural phenomenon that develops during nail growth. The methyl group marked in the diagram below is a manufacturing base for keratinocytes, which keep making new keratinocytes and keep the nail growing. The newly produced keratin cells are still fresh, round and white. These newborn cells push the cells of the previous generation outward. As they push their way up to the nail root, the cells of the previous generation are squeezed flatter and flatter and gradually die and begin to harden (and because they are out of the nerve range of the nail, it doesn’t hurt to cut the nail). By the time the cells of the previous generation enter the visible part of the nail bed, most of the keratin cells have been “squeezed” to become translucent and have hardened like small shields to protect the nail bed. Because the growth rate of the nail is decreasing from the center to the sides, the time required for the keratinocytes to become translucent does not change depending on their location, thus creating this arc of white and translucent junction. If the white arc is just exposed, it is what we call a crescent mark. See, it’s just a nail that is not fully keratinized. Thumbs often have them, pinkies often don’t. Nails that love to work grow quickly. The thumb is the model of labor of the five fingers, the nail wears out quickly, so it naturally grows fast and the crescent is easily pushed out. This explains why most people have crescents on their thumbs, because the thumb is used very frequently. The pinky finger, on the other hand, is less labor-intensive compared to the other four fingers, so the growth of the pinky nail is slower than the other four fingers. Therefore, the crescent of the little finger is less common. This is probably the origin of the saying “8 moons are just right, 10 moons are harmful”. But there is no scientific basis for this, because those who often play the piano or violin, because the frequency of use of the pinky finger than normal people, pinky nail growth speed up, so the crescent moon will also emerge. There are also some people whose nails naturally grow fast, so the pinky finger will also have a crescent. Suddenly invisible or suddenly appearing, there is a problem Although there are differences in the growth rate of the nails of the five fingers, the growth rate of the nails of the left and right hands is roughly the same, and there is no significant difference because of the right lipped hand or the left lipped hand. Therefore, the lunulae on the two fingers are basically symmetrical. Occasionally, a person may have one more or one less crescent, but this is just a normal change in the body’s metabolism that makes the nail growth rate vary a little, so don’t worry about it. Sometimes, however, changes in the crescent moon do reflect some health problems. The premise is – your crescent is just becoming very different from what you used to have! Not that your crescent is different from others. If, in a short period of time, you go from having no moon teeth to suddenly having a lot of full moon teeth, or if all of your otherwise full moon teeth are suddenly invisible, then be careful if you have a thyroid problem. Hyperthyroidism will make the entire body’s metabolism become fast, and the growth of nails is no exception. As a result, keratin, which is already a bit hard but not yet faded to translucent, can be very abundant. As a result, people without a lunula will have full lunulae, and those with lunulae will have lunulae that become larger and larger. In the case of hypothyroidism, it is just the opposite, the whole body’s metabolism becomes very slow and the nail growth slows down or even tends to stop. If the keratin has matured and there is no new supply, the crescent will naturally become smaller and smaller until it disappears. When you are seriously ill or malnourished, the nail does not get enough nutrients to produce keratin cells, which may also cause the crescent to disappear. In addition, as we get older, the body’s metabolism slows down and the crescent will be a little smaller than when we were younger. Here are a few of the nails that have gone wrong 1. yellow nails Occasional yellowing of the nails is usually not a big deal: women who often wear dark nail polish will also have some slightly yellow nails after removing the polish, and usually let the nails run around naked for a while and they will return to normal. In addition to nail polish, nails can also turn yellow if you eat too many carrots. The warning sign of yellow nails is usually: a fungal infection. If the infection is severe, it can also lead to atrophy of the nail bed, thickening or even chipping of the nail. A poorly sanitized nail salon is the perfect place for fungus and bacteria to spread. However, if your nails are yellow all the time, then this could be a serious thyroid disease, lung disease, diabetes, or psoriasis. 2, pockmarked face nails The pockmarks or small ripples on the face of the nail affect not only the aesthetics, but also suggest that you may have just suffered from psoriasis or inflammatory arthritis. If you suffer from psoriasis, the nail bed of your nails will often turn reddish-brown. Although psoriasis is a skin disease, some people have early symptoms of just nail lesions, which can make it difficult for doctors to diagnose. Since psoriasis is relatively hereditary, it is a good idea to write in your medical history if someone in your family has had the disease to help your doctor make a better diagnosis. However, if you only have a few scattered dots on your hands, there is no need to panic, it’s just meth malnutrition. 3, loss of blood color nails Because of the rich capillaries in the nail bed below the nail plate, a beautiful pink color comes through on the translucent nails, making it obvious at first glance that they are healthy. Because of age, the blood vessels at the end of the limbs of older people are less full than those of younger people, and their nails look paler than those of younger people, which is just a sign of normal aging. However, in addition to aging, the pale nails can also be caused by anemia or malnutrition, liver disease, congestive heart failure, etc. These diseases all somehow make the end of the limb blood vessel filling insufficient. If the disease continues to worsen, it is not as simple as pallor. The nail may become flat or even sunken in the center making the nail spoon shaped and the color may change from pale to bruised. 4. A nail full of black lines If the nail has not been traumatized, but black lines suddenly appear underneath and spread to the surrounding skin, it is likely that melanoma is at work. Although melanoma is not as mysterious as in the movie, it is still a very dangerous skin cancer, so don’t delay and go to the hospital for examination as soon as possible. In addition, look, the nails full of black lines still have clear and full crescent marks. It is clear that the presence or absence of crescent marks is not so closely related to health.